The objective of the research is to compare myeloma IgD Fc fragments with membrane bound Fc fragments and to correlate serum IgD levels to IgD synthesized in vitro by peripheral blood lymphocytes. This will be achieved by the following experiments: 1. CNBr fragments of myeloma and cell membrane bound IgD will be compared in polyacrylamide gels. It will be investigated if membrane bound delta chains have methionine as the COOH terminal residue as was demonstrated for serum delta chains. 2. Peripheral blood lymphocytes will be cultured in vitro and the IgD concentration in the supernatant quantitated by a solid phase radioimmunoassay. The in vitro formed IgD will be compared to the serum IgD level to determine whether there is a relationship in normals and patients with kidney disease and cancer in which higher IgD serum levels were found than in controls. 3. Employing growth factor containing supernatants of mitogen activated peripheral blood lymphocytes, B cell lines will be established. These cells will be analyzed for cell bound IgM and IgD to determine the role of cell bound IgD for differentiation of B cells to plasma cells.